How to select all child nodes on selecting parent in kendo TreeList? javascript
Question
I'm trying to select child nodes on parent node clicked. I couldn't find any example for select api. Should i use checkbox instead?
<button id="btn">Highlight third row</button>
<div id="treeList"></div>
<script>
$("#treeList").kendoTreeList({
columns: [
{ field: "id" },
{ field: "name" },
{ field: "age" }
],
dataSource: [
{ id: 1, parentId: null, name: "Jane Doe", age: 22, expanded: true },
{ id: 2, parentId: 1, name: "John Doe", age: 24 },
{ id: 3, parentId: 1, name: "Jenny Doe", age: 3 }
],
selectable: "multiple row"
});
</script>
I am trying to do that if select "1" (top parent), select 2,3 (child nodes). Hope there is native solution for javascript implementation. Thanks in advice!
1 answers
solution1
0 2020-03-01 03:56:40
The selection state is maintained by TreeList in the data items row rendering <tr k-state-selected> , and that state is not reflected in the TreeList dataSource . Also, the data source is the only place the child relationship is discoverable. So there is a bit of back and forth to deal with selections and children.
Also TreeList does not have a select event like TreeView so out of the box you do not know which nodes were selected or deselected.
The change event fires when one action causes one or more rows (like shift-click can do) are caused to be selected or deselected. Within your change handler you can only know the current state of all selected rows using the select() method.
Thus, within change , you need to track prior selection state and current selection state to find which rows changed selection state, which would merit their children to be selected or deselected according to your requirement.
See this Dojo for an example. It's not perfect because in the change event you can only determine selected nodes and not know if a 'reselection' occurred (ie clicked on a selected row again). Anyway, the descent down the hierarchy of the TreeList is performed recursively and relies on the dataSource data item property .hasChildren and dataSource method .childNodes()
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>TreeList select (change)</title>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2020.1.219/styles/kendo.common.min.css">
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2020.1.219/styles/kendo.rtl.min.css">
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2020.1.219/styles/kendo.default.min.css">
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2020.1.219/styles/kendo.mobile.all.min.css">
<script src="https://code.jquery.com/jquery-1.12.3.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2020.1.219/js/angular.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2020.1.219/js/jszip.min.js"></script>
<script src="https://kendo.cdn.telerik.com/2020.1.219/js/kendo.all.min.js"></script></head>
<body>
<p><a target="_blank" href="https://docs.telerik.com/kendo-ui/api/javascript/ui/treelist">TreeList docs</a></p>
<div id="treeList"></div>
<script>
selected_uids = []; // track selected uids
autoselecting = false;
$("#treeList").kendoTreeList({
columns: [
{ field: "id" },
{ field: "name" },
{ field: "age" }
],
dataSource: [
{ id: 1, parentId: null, name: "Jane Doe", age: 22, expanded: false },
{ id: 2, parentId: 1, name: "John Doe", age: 24 },
{ id: 3, parentId: 1, name: "Jenny Doe", age: 3 },
{ id: 4, parentId: null, name: "Jane Mack", age: 22, expanded: false },
{ id: 5, parentId: 4, name: "John Mack", age: 24 },
{ id: 6, parentId: 4, name: "Jenny Mack", age: 3 }
],
selectable: "multiple row",
change: function(e) {
if (autoselecting) {
e.preventDefault();
return;
}
debugger;
autoselecting = true;
var selected_rows = this.select();
console.log ('desel',selected_rows, selected_uids);
// check for new deselections
for (var index = 0; index < selected_uids.length; index++) {
var selected_uid = selected_uids[index];
if (selected_uid) {
var row = $("tr[data-uid='" + selected_uid + "'].k-state-selected");
if (row.length == 0) {
// no such selected row for one that was previously tracked as selected
deselectChildren(this, selected_uid);
selected_uids[index] = null; // untrack
}
}
}
var selected_rows = this.select();
console.log ('sel',selected_rows,selected_uids);
// check for new selections
for (var index = 0; index < selected_rows.length; index++) {
var data = this.dataItem(selected_rows[index]);
console.log('data',data);
if (jQuery.inArray(data.uid, selected_uids) == -1) {
// new selection
selected_uids.push(data.uid);
selectChildren(this, data);
}
}
for (var i=0, j=0; i < selected_uids.length; i++) {
if (selected_uids[i] != null) {
if (i > j) {
selected_uids[j] = selected_uids[i];
}
j++;
}
}
selected_uids.length = j;
autoselecting = false;
},
});
function selectChildren(treeList, data) {
if (!data.hasChildren) return;
var children = treeList.dataSource.childNodes(data);
for (var index = 0; index < children.length; index++) {
var child = children[index];
if (jQuery.inArray(child.uid, selected_uids) == -1) {
selected_uids.push(child.uid);
treeList.select($("tr[data-uid='" + child.uid + "']"));
selectChildren(treeList,child);
}
}
}
function deselectChildren(treeList, uid) {
var data = treeList.dataSource.getByUid(uid);
if (!(data && data.hasChildren)) return;
var children = treeList.dataSource.childNodes(data);
for (var index = 0; index < children.length; index++) {
var child = children[index];
var row = $("tr[data-uid='" + child.uid + "'].k-state-selected");
if (row.length == 1) {
var at = selected_uids.indexOf(child.uid);
if (at >= 0) selected_uids[at] = null;
row.removeClass('k-state-selected');
}
deselectChildren(treeList,child.uid);
}
}
$("#treeList").data("kendoTreeList").select($("#treeList tbody>tr:nth(0)"));
</script>
</body>
</html>
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